Self-light emitting device and method of manufacturing the same

ABSTRACT

To provide a process of successively forming from an EL layer, a cathode, a barrier layer and a cover layer in the same multi-chamber. By using a same film deposition method to form the EL layer and the cover layer, as shown in FIG.  1 A, the EL layer, the cathode, the barrier layer, and the cover layer can be formed in the same multi-chamber in succession. Thus, as shown in FIG.  1 B, a sealed structure of an EL element can be formed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a self-light emitting device that hasan EL element formed over an insulating member and constructed of aluminous organic material (hereinafter referred to as organic ELmaterial) capable of obtaining EL (Electro Luminescence) sandwichedbetween an anode and a cathode, and to a method of manufacturing anelectric appliance having the self-light emitting device as a displayunit (a display or a display monitor). It is to be noted that theabove-mentioned self-light emitting device is also referred to as anOLED (Organic Light Emitting Diodes).

2. Description of the Related Art

In recent years, the development of a display device (self-lightemitting device) using as an EL element a self-light emitting elementthat utilizes the EL phenomenon of a luminous organic material isproceeding. The self-light emitting device is a self-emissive typedevice and, hence, unlike a liquid crystal display device, does not needa back light. In addition, the self-light emitting device has a wideangle of view, and therefore is perceived as a prospective display unitfor electric appliances.

Note that the EL element is composed of a layer containing an organiccompound from which electro luminescence (luminescence generated byapplying an electric field) can be obtained (hereinafter referred to asEL layer), an anode layer, and a cathode layer. There are two types ofluminescence in an organic compound, one being a luminescence that isgenerated in returning to a ground state from a singlet excitation state(fluorescence) and the other being a luminescence that is generated inreturning to a ground state from a triplet excitation state(phosphorescence). The present invention may be applied to either typeof luminescence.

There are two kinds of self-light emitting device: a passive type(simple matrix type) and an active type (active matrix type), and bothtypes are being developed actively. In particular, the active matrixtype self-light emitting device is currently attracting much attention.In the EL materials for the EL layer which can be said as the core ofthe EL element, researches are being made on low molecular based organicEL materials and high molecular based organic EL materials (polymerbased). The polymer type organic EL materials are particularly highlyregarded since they are easier to handle and have higher heat resistancein comparison with the low molecular based organic EL materials.

A method in which an application is controlled by an electric field andan ink-jet method proposed by Seiko-Epson, Co. can be cited as filmdeposition methods for the polymer type organic EL materials.

According to the present invention, the same method is used to form theEL layer and a film made of an organic material (organic resin) (thefilm will hereinafter be referred as a cover layer) that is formed overthe EL element and covering the EL element. It is to be noted that thecover layer is a layer made of an organic material and which will beformed over the cathode of the EL element composed of an anode, an ELlayer, and a cathode. The provision of this cover layer is effective forthe stress relaxation of the TFT or the EL element. Further, thepermeation of moisture and oxygen into the EL layer can be prevented,whereby the degradation of the EL layer can be prevented. By furtherforming a film made of an inorganic material (hereinafter referred to asa barrier layer) on the cover layer, moisture and oxygen can beprevented from permeating into the cover layer or the EL layer.

SUMMARY OF THE INVENTION

It is to be noted that the present invention has an object to provide aprocess of successively forming an EL layer, a cathode, a barrier layer,and a cover layer in the same multi-chamber.

Further, another object of the present invention is to form the coverlayer at a desirable position with good control. In addition, a furtherobject of the present invention is to provide a self-light emittingdevice that employs such means and a method of manufacturing the same,and to provide an electric appliance having such a self-light emittingdevice as its display unit.

The multi-chamber employed for the purpose of attaining the above objectis a film deposition device which has an application chamber for formingthe EL layer and the cover layer made of an organic material by the inkjet method or the electric field application method, an evaporationchamber for forming the cathode by evaporation, and a sputtering chamberfor forming the barrier layer made of silicon nitride or tantalum oxide.

It is to be noted that, in the present invention, in the case of formingthe EL layer by application of a solution in which an EL material isdissolved in a solvent, then this solution is provided in a materialchamber. The solution is referred as an application liquid throughoutthe present specification. When the application liquid becomes atomizedand has an electric charge, then the application liquid is controlled bythe electric field that is imparted by the electrodes, whereby the ELlayer is formed over a substrate at the application position.

Further, for the cover layer, an organic resin liquid for forming anorganic resin film is provided in the material chamber. The cover layeris formed by an application method that is similar to that for theformation of the EL layer.

Note that in the present invention the barrier layer may be formed afterforming the cover layer on the cathode of the EL element, or thestructure thereof may be one in which the cover layer is formed afterforming the barrier layer on the cathode of the EL element.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbe more apparent from the following description taken in conjunctionwith the accompanying drawings:

FIGS. 1A to 1C are diagrams showing a thin film formation method of thepresent invention;

FIG. 2 is a diagram showing a cross-sectional structure of a pixelportion:

FIGS. 3A and 3B are diagrams showing a top view structure of a pixelportion and a configuration thereof, respectively;

FIGS. 4A to 4E are views showing a manufacturing process of a self-lightemitting device:

FIGS. 5A to 5D are views showing a manufacturing process of a self-lightemitting device:

FIGS. 6A to 6C are views showing a manufacturing process of a self-lightemitting device;

FIGS. 7A and 7B are views showing a cross-sectional structure of a TFTof a pixel portion:

FIGS. 8A and 8B are views showing a cross-sectional structure of a TFTof a pixel portion:

FIGS. 9A and 9B are views showing the outer appearance of a self-lightemitting device:

FIG. 10 is a diagram illustrating a circuit block configuration of aself-light emitting device;

FIG. 11 is a diagram showing a cross-sectional structure of an activematrix type self-light emitting device;

FIG. 12 is a diagram showing a thin film formation method:

FIG. 13 is a diagram showing a cross-sectional structure of a passivetype self-light emitting device;

FIG. 14 is a diagram showing a cross-sectional structure of a passivetype self-light emitting device;

FIGS. 15A to 15F are views showing concrete examples of electricappliances; and

FIGS. 16A and 16B are views showing concrete examples of electricappliances.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment mode of the present invention will be explained here withreference to FIGS. 1A to 1C. As shown in FIG. 1A, an EL layer, acathode, a barrier layer, and a cover layer can be successively formedin the same multi-chamber.

It is to be noted that the barrier layer is referred to as a passivationfilm provided for the purpose of preventing moisture and oxygen frompenetrating into the EL layer and formed of an inorganic material.

First, the EL layer is formed in the application chamber by employingthe electric field application method or the ink jet method. The cathodeis formed next in the evaporation chamber by means of evaporation, andthe barrier layer is further formed on the cathode. Using sputtering orplasma CVD, the barrier layer is formed of an inorganic film that ismade of an inorganic material such as silicon nitride, tantalum oxide,aluminum nitride, or diamond-like carbon (DLC) made of carbon. Finally,on top of the barrier layer, the cover layer is formed in theapplication chamber by means of the ink jet method, similar to theformation of the EL layer, thereby completing the sealing structure ofthe self-light emitting device.

As thus explained, because the same method is used in forming the ELlayer and the cover layer, the layers may be selectively formed only atthe desired positions and may be processed in the same chamber.

The sectional structure of a lamination film formed in the presentinvention is shown in FIG. 1B. In FIG. 1B, reference numeral 101 denotesa glass substrate and reference numeral 102 denotes a current controlTFT. Furthermore, reference numeral 103 denotes a pixel electrode thatis made of a transparent conductive film electrically connected to thecurrent control TFT. An EL layer 104 is formed on the pixel electrode103 by using the above-mentioned method, and a cathode 105 is furtherformed on the EL layer 104 by evaporation.

In addition, a barrier layer 106 made of an inorganic film such assilicon nitride, tantalum oxide, or DLC film made of carbon, is formedon the cathode 105. After the formation of the barrier layer 106, acover layer 107 made of an organic resin film is formed thereon by usingthe application method that is the same as the EL layer.

Shown in FIG. 1C is the electric field application method in which theapplication liquid is controlled by an electric field for application inthe formation of the EL layer and the cover layer 107.

In FIG. 1C, reference numeral 110 denotes the substrate with theformation of up to the barrier layer in the lamination structure shownin FIG. 1B. Reference numeral 111 denotes a material chamber that isprovided with an organic resin liquid for forming the cover layer. Inthe material chamber 111, an ultrasonic oscillator 112 is provided, andan electrode 114 is provided on a nozzle 113 at the tip of the materialchamber 111, where the organic resin liquid is to be discharged.

In the case of the present invention, the organic resin liquid isatomized in the material chamber 111 through the impartation ofultrasonic oscillation to the ultrasonic oscillator 112. The organicresin liquid that has become atomized here is charged and turned intocharged particles by the electrode 114 provided on the nozzle 113 of thematerial chamber 111, thereby forming the EL layer and the cover layerat desirable positions on the active matrix substrate 110.

A leading electrode 115 extracts the organic resin liquid that hasbecome charged particles from the nozzle 113, an accelerating electrode116 accelerates the charged particles in a flying direction. Further, acontrolling electrode 117 controls the application position to therebyapply the liquid on the desired position of the substrate 110.

Thus, the sealing structure of the self-light emitting device in whichthe lamination structure shown in FIG. 1B can be formed in the samemulti-chamber, is completed.

Note that FIG. 1B shows a case where the cover layer made of an organicmaterial is formed after the formation of the barrier layer made of aninorganic material to cover the EL element. However, in the presentinvention, the barrier layer made of an inorganic material may be formedafter the formation of the cover layer made of an organic material tocover the EL element.

Embodiment 1

FIG. 2 is a sectional view of a pixel portion of an EL display device ofthe present invention, FIG. 3A is a top view thereof, and FIG. 3B is aview showing its circuit structure. Actually, pixels are arranged in amatrix form to form a pixel portion (image display portion).Incidentally, a sectional view taken along A-A′ of FIG. 3A correspondsto FIG. 2. Thus, since common numerals are used in FIG. 2 and FIGS. 3Aand 3B, reference may be suitably made to the both drawings. Althoughthe top view of FIG. 3 shows two pixels, both have the same structure.

In FIG. 2, reference numeral 11 designates a substrate; and 12, aninsulating film (hereinafter referred to as an under film) which becomesan under layer. As the substrate 11, a substrate made of glass, glassceramic, quartz, silicon, ceramic, metal or plastic can be used.

Although the under film 12 is effective especially in the case where asubstrate including a movable ion or a conductive substrate is used, itis not necessary to provide the under film on a quartz substrate. As theunder film 12, an insulating film containing silicon may be used. In thepresent specification, the “insulating film containing silicon”indicates an insulating film containing silicon, oxygen, or nitrogen ata predetermined ratio, such as a silicon oxide film, a silicon nitridefilm, or a silicon nitride oxide film (expressed by SiOxNy).

To dissipate heat of a TFT by making the under film 12 have a heatradiation effect is effective also in preventing deterioration of theTFT or deterioration of the EL element. Any well-known materials can beused for providing the heat radiation effect.

Here, two TFTs are formed in a pixel. Reference numeral 201 designates aswitching TFT which is formed of an n-channel TFT; and 202, a currentcontrolling TFT which is formed of a p-channel TFT.

However, in the present invention, it is not necessary that theswitching TFT is limited to the n-channel TFT and the currentcontrolling TFT is limited to the p-channel TFT, but a modification canbe made such that the switching TFT is made the p-channel TFT and thecurrent controlling TFT is made the n-channel TFT, or both use then-channel TFTs or the p-channel TFTs.

The switching TFT 201 includes a source region 13, a drain region 14,LDD region 15 a to 15 d, an active layer including a high concentrationimpurity region 16 and channel formation regions 17 a and 17 b, a gateinsulating film 18, gate electrodes 19 a and 19 b, a first interlayerinsulating film 20, a source wiring 21, and a drain wiring 22.

Besides, as shown in FIGS. 3A and 3B, the gate electrodes 19 a and 19 bhave a double gate structure in which they are electrically connected toa gate wiring 211 formed of another material (material having resistancelower than the gate electrodes 19 a and 19 b). Of course, not only thedouble gate structure, but also a single gate or a so-called multigatestructure (structure including an active layer having at least twochannel formation regions connected in series) such as a triple gatestructure may be adopted. The multigate structure is very effective indecreasing an off current value, and in the present invention, theswitching element 201 of the pixel is made the multigate structure sothat the switching element having a low off current value is realized.

The active layer is formed of a semiconductor film containing acrystalline structure. That is, a single crystal semiconductor film maybe used, a polycrystalline semiconductor film or a microcrystallinesemiconductor film may be used. The gate insulating film 18 may beformed of an insulating film containing silicon. Any conductive film maybe used for the gate electrode, the source wiring or the drain wiring.

Further, in the switching TFT 201, the LDD regions 15 a to 15 d areprovided not to overlap with the gate electrodes 19 a and 19 b throughthe gate insulating film 18. This sort of structure is very effective indecreasing the off current value.

Note that it is further preferable to provide an offset region (regionmade of a semiconductor layer of the same composition as the channelformation region and a gate voltage is not applied) between the channelformation region and the LDD region, in view of decreasing the offcurrent value. In the case of the multigate structure having at leasttwo gate electrodes, the high concentration impurity region providedbetween the channel formation regions is effective in decreasing the offcurrent value.

Next, the current controlling TFT 202 includes an active layer includinga source region 31, a drain region 32 and a channel formation region 34,a gate insulating film 18, a gate electrode 35, a first interlayerinsulating film 20, a source wiring 36, and a drain wiring 37. Althoughthe gate electrode 35 has a single gate structure, a multigate structuremay be adopted.

As shown in FIG. 3, the drain of the switching TFT is connected to thegate of the current controlling TFT 202. Specifically, the gateelectrode 35 of the current controlling TFT 202 is electricallyconnected to the drain region 14 of the switching TFT 201 through thedrain wiring (which can also be called a connection wiring) 22. Thesource wiring 36 is connected to a power supply line 212.

The current controlling TFT 202 is an element for controlling thequantity of current injected to an EL element 203, and it is notpreferable to cause a large amount of current to flow in view ofdeterioration of the EL element. Thus, it is preferable to design achannel length (L) to be sufficiently long so that excessive currentdoes not flow through the current controlling TFT 202. It is designed todesirably make the current 0.5 to 2 μA per pixel (preferably 1 to 1.5μA).

The length (width) of the LDD region formed in the switching TFT 201 ismade 0.5 to 3.5 μm, typically 2.0 to 2.5 μm.

As shown in FIG. 3A, a wiring containing the gate electrode 35 of thecurrent control TFT 202 is overlaped with a power source supply line 212through an insulating film in a region denoted by the reference numeral50. A storage capacitor (condenser) is formed in the region denoted bythe reference numeral 50. It is also possible use a capacitor formed bya semiconductor film 51, an insulating film (not shown in the figure) inthe same layer as the gate insulating film, and the power source supplyline 212 as the storage capacitor. The storage capacitor 50 functions asa condenser for maintaining the voltage applied to the gate electrode 35of the current control TFT 202.

From the viewpoint of increasing the quantity of current which can flow,it is also effective to increase the thickness (preferably 50 to 100 nm,more preferably 60 to 80 nm) of the active layer (especially the channelformation region) of the current controlling TFT 202. On the contrary,in the case of the switching TFT 201, from the viewpoint of decreasingthe off current value, it is also effective to decrease the thickness(preferably 20 to 50 nm, more preferably 25 to 40 nm) of the activelayer (especially the channel formation region).

Next, reference numeral 38 designates a first passivation film, and itis appropriate that its film thickness is made 10 nm to 10 μm(preferably 200 to 500 nm). As its material, an insulating filmcontaining silicon (especially a silicon nitride oxide film or a siliconnitride film is preferable) can be used.

A second interlayer insulating film (which may be called a flatteningfilm) 39 is formed on the first passivation film 38 to cover therespective TFTs, so that a step formed by the TFTs is flattened. As thesecond interlayer insulating film 39, an organic resin film ispreferable, and it is preferable to use polyimide, polyamide, acrylicresin, BCB (benzocyclobutene) or the like. Of course, if sufficientflattening can be made, an inorganic film may be used.

It is very important to flatten the step, which is produced by the TFT,through the second interlayer insulating film 39. Since an EL layerformed later is very thin, there is a case where poor luminescenceoccurs due to existence of a step. Accordingly, it is desirable to makeflattening before a pixel electrode is formed, so that the EL layer canbe formed on the flattest surface as much as possible.

Reference numeral 40 designates a pixel electrode (corresponding to ananode of the EL element) made of a transparent conductive film, andafter a contact hole (opening) is formed in the second interlayerinsulating film 39 and the first passivation film 38, the pixelelectrode is formed to be connected to the drain wiring 37 of thecurrent controlling TFT 202 at the formed opening portion.

In this embodiment, a conductive film made of a compound of indium oxideand tin oxide is used as the pixel electrode. Besides, a small amount ofgallium may be added to this. Further, a compound of indium oxide andzinc oxide or a compound of zinc oxide and gallium oxide can also beused. Note that a recess produced after a pixel electrode is formed on acontact hole is called an electrode hole in this specification.

After the pixel electrode is formed, banks 41 made of resin material areformed. The banks 41 are formed by patterning an acrylic resin film or apolyimide film having a thickness of 1 to 2 μm. The banks 41 arerespectively formed like a stripe between pixel arrays. In thisembodiment, although they are formed along the source wiring 21, theymay be formed along the gate wiring 35.

Next, an EL layer 42 is formed with the electric field applicationmethod as explained in FIG. 1C. Although only one pixel is shown here,EL layers corresponding to the respective colors of R (red), G (green)and B (blue) are formed.

As the organic EL material used for the EL layer, a polymer material isused. As a typical polymer material, polyparaphenylene vinylene (PPV),polyvinylcarbazole (PVK), polyfluorene or the like is named.

Although there are various types as the PPV organic EL material, forexample, the following molecular formula is published (“H. Shenk, H.Becker, O. Gelsen, E. Kluge. W. Kreuder, and H. Spreitzer, “Polymers forLight Emitting Diodes”, Euro Display, Proceedings, 1999, p. 33-37”).

Besides, polyphenylvinyl of a molecular formula disclosed in JapanesePatent Application Laid-open No. Hei. 10-92576 can also be used. Themolecular formula as follows:

Besides, as the PVK organic EL material, there is a molecular formula asfollows:

The polymer organic EL material can be dissolved in a solvent when it isin a state of polymer and can be coated, or can be dissolved in asolvent when it is in a state of monomer and can be polymerized aftercoating. In the case where it is coated in the state of monomer, apolymer precursor is first formed and is polymerized by heating invacuum so that a polymer is formed.

As a specific EL layer, it is appropriate thatcyanopolyphenylenevinylene is used for the EL layer emitting red light,polyphenylenevinylene is used for the EL layer emitting green light, andpolyphenylenevinylene or polyalkylphenylene is used for the EL layeremitting blue light. It is appropriate that its thickness is made 30 to150 nm (preferably 40 to 100 nm).

However, the above examples are merely examples of the organic ELmaterial which can be used as the EL layer of the present invention, andit is not necessary to limit the material to these. In this embodiment,the mixture of the organic EL material and the solvent is coated withthe electric field application system shown, and the solvent isvolatilized to remove, so that the EL layer is formed. Accordingly, aslong as the combination is such that the temperature when the solvent isvolatilized does not exceed the glass transition temperature of the ELlayer, any organic EL material may be used, a low molecular materialwhich is not mentioned here, or a high molecular material with a lowmolecular material may be used.

Toluene, xylene, chlorobenzene, dichlorobenzene, anisole, chloroform,dichloromethane, -butyl lactone, butyl cellosolve, cyclohexane, NMP(N-methyl-2-pyrolidone), cyclohexanone, dioxane, or THF(tetrahydrofuran) are exemplified as typical solvents. It is to be notedthat a solution in which the above-mentioned EL material is dissolved isreferred as an application liquid throughout the present invention.Further, it is preferable that the viscosity of the application liquidis between 1×10⁻³ and 3×10⁻² Pa's.

First, the application liquid prepared in the material chamber 111 isatomized by the ultrasonic oscillator 112 as shown in FIG. 1C. When theatomized application liquid become charged particles through theinfluence of an electric field from the electrode 114 that is providedon the nozzle 113, then the application liquid is extracted from thenozzle 113 by the leading electrode 115. After the extracted applicationliquid is accelerated by the accelerating electrode 116, the applicationliquid is then controlled by the controlling electrode 117 and appliedon the desired position. The EL layer is thus formed. It is to be notedthat the application liquid is charged by the influence of the electricfield of the electrode 114 that is attached to the nozzle 113 at themoment pf spurting out from the material chamber 111, whereby it becomescharged particles.

In the present invention, first, the application liquid for a red colorEL layer that is provided in the material chamber 111, is atomized andcontrolled by an electric field, then applied to thereby form a row ofpixels to luminesce a red color. Next, while moving the substrate bythree rows in the direction of the adjacent row of pixels, the formationof rows of pixels to luminesce the red color is carried out at every tworows. The application liquid for a green color EL layer that is preparedin the material chamber 111 is next applied in the same way to therebyform rows of pixels to luminescence the green color at every two rows.Furthermore, the application liquid for a blue color EL layer that isprepared in the material chamber 111 is applied in the same way as theothers to thereby form rows of pixels to luminescence the blue color.

By performing the above operation, a plurality of three rows of red,green, and blue pixels lined up in stripe shapes can be formed on thesubstrate.

Note that every time the kind of application liquid for the EL layer ischanged, the material chamber 111 that is provided with the applicationliquid for the EL layer may be changed together therewith, or thematerial chamber 111 may be used with only changing the applicationliquids and not the material chamber. In addition, the nozzle 113 thatis attached to the material chamber 111 is not limited to one nozzle,but two or more nozzles may be attached.

Further, although not used herein, a mask may be provided between thematerial chamber 111 and the substrate to thereby control the positionson the substrate at which the application liquid is via the mask. It isto be noted that the material chamber 111 and the mask may be providedseparately, or they may be integrated into the device.

During the formation of the EL layer 42, the atmosphere for processingis an atmosphere that contains little moisture and oxygen because the ELlayer is easily degraded due to the presence of moisture and oxygen.That is, it is desirable to perform the formation of the EL layer in aninert gas such as nitrogen or argon. Further, an atmosphere of thesolvent that is employed in preparing the application liquid may beemployed as the atomosphere for processing scince the evaporation rateof the application liquid can be controlled.

Thus, after forming the EL layer 42, a cathode 43 made of a lightshielding conductive film and a protective electrodeb 44 are formed. InEmbodiment 1, a conductive film made of MgAg is used as the cathode 43and a conductive film made of aluminum is used as the protectiveelectrode 44.

It is to be noted that the above-mentioned EL layer is inferior to heat,and therefore it is desirable that the cathode 43 is formed at a thepossiblelowest temperature (preferably within the temperature range fromroom temperature to 120° C.). Accordingly, plasma CVD and sputtering areobserved as desirable film deposition methods. Further, the substratecompleted up to this point is referred as an active matrix substratethroughout the present specification.

In the present invention, after forming a barrier layer 45 that is madeof an inorganic film such as silicon nitride, tantalum oxide, or carbon,a cover layer 46 that is made of an organic resin film is formed byusing the electric field application method explained in FIG. 1C. Apreferred viscosity of the organic resin liquid that is used for formingthe cover layer 46 at this point is set between 1×10⁻³ and 3×10⁻² Pa.s.In addition, the film thickness of the cover layer formed at this pointis preferably 0.1 μm to 20 μm. However, it is possible to make the filmthickness thereof thicker than the above stated range by repeating theapplication and drying processes.

The sealing of the self-light emitting device is completed when thecover layer 46 is formed. However, a sealing substrate such as a glasssubstrate, a quartz substrate, or a plastic substrate may be provided onthe cover layer 46 to thereby complete the sealing structure of theself-light emitting device. It is also to be noted that the cover layer46 may be made to have the role of functioning as an adhesive forbonding the active matrix substrate and the sealing substrate.

Note that as a countermeasure against moisture and oxygen which arecause of degrading the EL layer, a dry agent or an anti-oxidant such asbarium oxide may be added into the cover layer made of an organic resinfilm.

Embodiment 2

In Embodiment 2 of the present invention, an explanation is made on amethod of manufacturing at the same time a pixel portion and a TFT of adriver circuit that is provided in the periphery of the pixel portionwith reference to FIGS. 4A to 6C. However, in order to simplify theexplanation, a CMOS circuit, which is the basic circuit for the drivercircuit, is shown in the figures.

First, as shown in FIG. 4A, a base film 301 is formed to a thickness of300 nm on a glass substrate 300. A lamination film constituting a 100 nmthick silicon oxynitride film and a 200 nm thick silicon oxynitride filmis used as the base film 301 in Embodiment 2. At this point, it isappropriate to set the nitrogen concentration of the silicon oxynitridefilm that is in contact with the glass substrate 300 to between 10 and25 wt %. Of course, an element may be directly formed on the quartzsubstrate without the provision of the base film.

Next, an amorphous silicon film (not shown in the figure) is formed to athickness of 50 nm on the base film 301 by using a known film depositionmethod. Note that the present invention is not necessarily limited tousing the amorphous silicon film, but a semiconductor film containing anamorphous structure (including a microcrystal semiconductor film) may beused. In addition, a compound semiconductor film containing an amorphousstructure such as an amorphous silicon germanium film may also be used,and the film thickness thereof may be between 20 and 100 nm.

The amorphous silicon film is then crystallized by a known method tothereby form a crystal silicon film (also referred to as polycrystalsilicon film or a polysilicon film) 302. Thermal crystallization usingan electric furnace, laser annealing crystallization using laser light,and lamp annealing crystallization using infrared light exist as knowncrystallization methods. Crystallization is performed in Embodiment 2using light from an excimer laser which uses XeCl gas.

Note that the pulse emission type excimer laser light processed into alinear shape is used in Embodiment 2, but a rectangular shape may alsobe used, and that continuous emission argon laser light and continuousemission excimer laser light can also be used.

In Embodiment 2, although the crystal silicon film is used as the activelayer of the TFT, it is also possible to use an amorphous silicon film.Furthermore, it is also possible to used the amorphous silicon to formthe active layer of the switching TFT, which requires a lowering of theOFF current value, while using the crystal silicon film to form theactive layer of the current controlling TFT. Carrier mobility is low inthe amorphous silicon film, and therefore it is difficult for a currentto flow therein, and as a result, it is difficult for an OFF current toflow. That is, the merits of both the amorphous silicon film in which itis hard to flow a current therein and the crystal silicon film in whichit is easy to flow a current therein can be utilized advantageously.

Next, as shown in FIG. 4B, a protective film 303 made of a silicon oxidefilm is formed to a thickness of 130 nm on the crystal silicon film 302.The thickness thereof may be chosen from the range of 100 to 200 nm(preferably between 130 and 170 nm). Furthermore, other films may alsobe used provided that they are insulating films containing silicon. Theprotective film 303 is provided so that the crystal silicon film is notdirectly exposed to plasma during the doping of an impurity, and so thatit is possible to have delicate concentration control of the impurity.

Resist masks 304 a and 304 b are then formed on the protective film 303,and an impurity element that imparts n-type conductivity (hereafterreferred to as an n-type impurity element) is doped therein through theprotective film 303. Note that elements belonging to the Group 15 aregenerally used as the n-type impurity element. Typically, phosphorous orarsenic can be used. Also note that in Embodiment 2, a plasma (ion)doping method in which phosphine (PH₃) is plasma activated withoutseparation of mass is used, and that phosphorous is doped at aconcentration of 1×10¹⁸ atoms/cm³. The ion implantation method, in whichseparation of mass is performed, may also be used, of course.

In an n-type impurity region 305 thus formed by this process, the doseamount of the n-type impurity element contained therein is regulated sothat the concentration thereof is 2×10¹⁶ to 5×10¹⁹ atoms/cm³ (typicallybetween 5×10¹⁷ and 5×10¹⁸ atoms/cm³).

Next, as shown in FIG. 4C, the protective film 303 and the resists 304 aand 304 b are removed to thereby activate the element belonging to Group15 that is doped therein. A known activation technique may be used asthe means of activation, and in Embodiment 2, activation is conducted byirradiation of an excimer laser light. Without being necessarily limitedto the use of the excimer laser light, a pulse emission type excimerlaser and a continuous emission type excimer laser may both, of course,be used. The aim here is the activation of the doped impurity element,and therefore it is preferable that irradiation is performed at anenergy level at which the crystal silicon film does not melt. Note thatthe laser irradiation may also be performed with the protective film 303in place.

It is to be noted that during the activation of the impurity element bylaser light, activation by heat treatment may also be performed alongtherewith. When activation is performed by heat treatment, consideringthe heat resistance of the substrate, it is appropriate to perform heattreatment on the order of 450 to 550° C.

Due to this process, edge portions of the n-type impurity region 305,that is, a boundary portion (connecting portion) and regions existing inthe periphery of the n-type impurity regions 305 and not doped with theimpurity element will become distinct. This means that, at the pointwhen the TFTs are later completed, extremely good connections can beformed between LDD regions and channel forming regions.

As shown in FIG. 4D, unnecessary portions of the crystal silicon filmare removed next to thereby form island-like semiconductor films(hereinafter referred to as active layers) 306 to 309.

Then, as shown in FIG. 4E, a gate insulating film 310 is formed coveringthe active layers 306 to 309. An insulating film containing silicon andhaving a thickness of 10 to 200 nm, preferably between 50 and 150 nm,may be used as the gate insulating film 310. The film thereof may take asingle layer structure or a lamination structure. A 110 nm thick siliconoxynitride film is used in Embodiment 2.

A 200 to 400 nm thick conductive film is formed next and patterned,thereby forming gate electrodes 311 to 315. The edge portions of thegate electrodes 311 to 315 may be formed into taper shapes. Note that inEmbodiment 2, the gate electrodes and lead wirings that are electricallyconnected to the gate electrodes (hereinafter referred to as gatewirings) are formed from different materials. Specifically, a materialhaving a lower resistance than that of the gate electrodes is used forforming the gate wirings. The reason for this resides in that a materialwhich is capable of being micro-processed is used as the gateelectrodes, and even if the material for the gate wirings cannot bemicro-processed, the material used for the wirings has low resistance.Of course, the gate electrodes and the gate wirings may also be formedfrom the same material.

Further, the gate electrodes may be formed from a single layerconductive film, and when necessary, it is preferable to use a two layeror a three layer lamination film. All known conductive films can be usedas the material for the gate electrodes. However, as stated above, it ispreferable to use a material which can be micro-processed, specifically,a material which can be patterned to a line width of 2 m or less.

Typically, it is possible to use a film made of an element selected fromthe group consisting of tantalum (Ta), titanium (Ti), molybdenum (Mo),tungsten (W), chromium (Cr), and silicon (Si), or a nitride filmcontaining the above elements (typically a tantalum nitride film,tungsten nitride film, or a titanium nitride film), or an alloy filmhaving a combination of the above elements (typically Mo—W alloy, Mo—Taalloy), or a silicide film of the above elements (typically a tungstensilicide film or a titanium silicide film). Of course, the films may beused as a single layer or a laminate layer.

A lamination film that is composed of a 50 nm thick tantalum nitride(TaN) film and a 350 nm thick tantalum (Ta) film is used in Embodiment2. These films may be formed by sputtering. Further, when an inert gassuch as Xe, Ne or the like is added as a sputtering gas, peeling of thefilms due to stress can be prevented.

At this point, the gate electrode 312 is formed so as to overlap aportion of the n-type impurity region 305 and sandwiching the gateinsulating film 310. This overlapping portion later becomes an LDDregion overlapping the gate electrode. Note that in a cross-sectionalview, the gate electrodes 313 and 314 can be seen as two electrodes, butthey are actually electrically connected.

Next, an n-type impurity element (phosphorous is used in Embodiment 2)is doped in a self-aligning manner using the gate electrodes 311 to 315as masks as shown in FIG. 5A. The doping of phosphorous is regulated sothat it can be doped into the impurity regions 316 to 323 thus formed ata concentration of {fraction (1/10)} to ½ that of the impurity regions305 and 306 (typically between ¼ and ⅓). Specifically, a concentrationof 1×10¹⁶ to 5×10¹⁸ atoms/cm³ (typically 3×10¹⁷ to 3×10¹⁸ atoms/cm³) ispreferable.

As shown in FIG. 5B, resist masks 324 a to 324 d are formed nextcovering the gate electrodes and the like, and an n-type impurityelement (phosphorous is used in Embodiment 2) is doped to thereby formimpurity regions 325 to 329 containing a high concentration ofphosphorous. Ion doping using phosphine (PH₃) is also performed here,and the concentration of phosphorous in these regions is regulated sothat it is between 1×10²⁰ and 1×10²¹ atoms/cm³ (typically between 2×10²⁰and 5×10²¹ atom/cm³).

A source region or a drain region of the N channel TFT is formed throughthis process, and in the switching TFT, a portion of the n-type impurityregions 319 to 321 formed through the process of FIG. 5A remains. Theseremaining regions correspond to the LDD regions 15 a to 15 d of theswitching TFT in FIG. 5.

Next, as shown in FIG. 5C, the resist masks 324 a to 324 d are removed,and a new resist mask 332 is formed. A p-type impurity element (boron isused in Embodiment 2) is then doped to thereby form impurity regions 333and 336 containing a high concentration of boron. Boron is doped here byion doping using diborane (B₂H₆) so that the concentration thereof is3×10²⁰ to 3×10²¹ atoms/cm³ (typically between 5×10²⁰ and 1×10²¹atoms/cm³).

Note that phosphorous has already been doped into the impurity regions333 to 336 at a concentration of 1×10²⁰ to 1×10²¹ atoms/cm³, but boronis doped here at a concentration of at least 3 times higher than that ofphosphorous. Therefore, the n-type impurity regions that have beenformed in advance are completely inverted to p-type conductivity, andfunction as p-type impurity regions.

Next, after removing the resist mask 332, the n-type and p-type impurityelements doped at respective concentrations are activated. Furnaceannealing, laser annealing, or lamp annealing may be performed as ameans of activation. Heat treatment is performed in Embodiment 1 under anitrogen atmosphere for 4 hours at 550° C. in an electric furnace.

It is important to remove as much as possible the oxygen contained inthe atmosphere at this point. This is because if any small traces ofoxygen exists, then the exposed surface of the electrode are oxidized,inviting an increase in resistance, and at the same time, it becomesmore difficult to make an ohmic contact later. It is thereforepreferable that the concentration of oxygen in the processingenvironment in the above activation process is set to 1 ppm or less,desirably 0.1 ppm or less.

After the activation process is completed, a gate wiring 337 is formednext to a thickness of 300 nm as shown in FIG. 5D. A metallic filmhaving aluminum (Al) or copper (Cu) as its principal component(occupying 50 to 100% as a composition) may be used as the material ofthe gate wiring 337. Regarding the placement of the gate wiring 337, itis formed so that the gate wiring 211 and the gate electrodes 19 a and19 b of the switching TFT (corresponding to gate electrodes 313 and 314of FIG. 4E) are electrically connected as in FIG. 3.

The wiring resistance of the gate wiring can be made extremely small byforming such type of structure, and therefore a pixel display region(pixel portion) having a large surface area can be formed. That is, thepixel structure of Embodiment 1 is extremely effective because aself-light emitting device having a screen size of a 10 inch diagonal orlarger (in addition, a 30 inch or larger diagonal) is realized due tothis structure.

Next, as shown in FIG. 6A, a first interlayer insulating film 338 isformed. As the first interlayer insulating film 336, either a singlelayer insulating film containing silicon is used, or a lamination filmin which 2 or more types of insulating film containing silicon arecombined may be used. Further, it is appropriate to set the filmthickness thereof between 400 nm and 1.5 μm. A structure in which an 800nm thick silicon oxide film is formed laminated on a 200 nm thicksilicon oxide nitride film is used in Embodiment 2.

Additional heat treatment is performed under an atmosphere containing 3%to 100% of hydrogen for 1 to 12 hours at a temperature of between 300°C. and 450° C. to thereby perform hydrogenation. This process is one forterminating the dangling bonds in the semiconductor film caused bythermally excited hydrogen. Plasma hydrogenation (using hydrogen excitedby a plasma) may be performed as another means of hydrogenation.

Note that the hydrogenation step may also be inserted between the stepof forming of the first interlayer insulating film 338. That is,hydrogenation processing such as the one above may be performed afterforming the 200 nm thick silicon oxide nitride film, and then theremaining 800 nm thick silicon oxide film may be formed thereafter.

Next, a contact hole is formed in the first interlayer insulating film338 and the gate insulating film 310 to thereby form source wirings 339to 342 and drain wirings 343 to 345. It is to be noted that inEmbodiment 2, this electrode is made of a lamination film of a threelayer structure in which a titanium film having a thickness of 100 nm,an aluminum film containing titanium and having a thickness of 300 nm,and a titanium film having a thickness of 150 nm are formed insuccession by sputtering. Of course, other conductive films may be used.

Next, a first passivation film 346 is formed to a thickness of 50 to 500nm (typically between 200 and 300 nm). A 300 nm thick silicon oxidenitride film is used as the first passivation film 346 in Embodiment 2.This may also be substituted with a silicon nitride film.

Note that it is effective to perform plasma process using a gascontaining hydrogen such as H₂ or NH₃ prior to the formation of thesilicon oxide nitride film. Hydrogen activated by this preprocess issupplied to the first interlayer insulating film 338, and the filmquality of the first passivation film 346 is improved by performing heattreatment. At the same time, the hydrogen added to the first interlayerinsulating film 338 diffuses to the lower layer side, and therefore theactive layers can be effectively hydrogenated.

Next, as shown in FIG. 6B, a second interlayer insulating film 347 madeof an organic resin is formed. As the organic resin, materials such aspolyimide, polyamide, acrylic resin, or BCB (benzocyclobutene) can beused. In particular, because the second interlayer insulating film 347is primarily used for leveling, acrylic resin that has excellentleveling properties is preferable. In Embodiment 2, an acrylic resinfilm is formed to a thickness sufficient to level a step differenceformed by TFTs. A preferred film thickness thereof is between 1 to 5 μm(more preferably between 2 and 4 μm).

A contact hole is formed in the second interlayer insulating film 347and the first passivation film 346 to thereby form a pixel electrode 348to be electrically connected to the drain wiring 345. In Embodiment 2,an indium tin oxide (ITO) film is formed to a thickness of 110 nm, andpatterning is carried out to thereby form the pixel electrode.Incidentally, as other materials, it is also possible to use a compoundin which 2 to 20% of zinc oxide (ZnO) is mixed in indium oxide or acompound constituting zinc oxide and gallium oxide may be used as atransparent electrode. The pixel electrode 348 becomes the anode of theEL element.

As shown in FIG. 6C, a bank 349 of a resin material is formed next. Thebank 349 may be formed of an acrylic resin film or a polyimide film,which has a total film thickness of between 1 to 2 μm, with patterning.The bank 349 is formed in stripe shapes between the rows of pixels asshown in FIG. 6C. In Embodiment 2, the bank 349 is formed along thesource wiring 341, but it may be formed along the gate wiring 337.

An EL layer 350 is formed next using the electric field applicationmethod explained with reference to FIG. 1C. It is to be noted thatalthough only one pixel is shown here, the EL layers corresponding tothe respective colors R (red), G (green), and B (blue) are formed asexplained in Embodiment 1.

First, the application liquid for forming the EL layer provided in thematerial chamber is atomized with ultrasonic oscillation by theultrasonic oscillator. When the atomized application liquid for formingthe EL layer is charged by an electric field imparted by a voltage thatis applied to the electrode, then the application liquid can beextracted by a leading electrode that is attached to the exterior of thematerial chamber. After the extracted EL layer application liquid isaccelerated by the accelerating electrode in a flying direction, theapplication liquid is then controlled by the controlling electrode tothereby be applied on the desired position on the substrate 110.

In the present invention, first, an application liquid for a red colorEL layer is extracted from the material chamber as an atomizedapplication liquid for forming the EL layer by the leading electrode.Then, after being accelerated by the accelerating electrode, theapplication liquid is controlled by the controlling electrode to therebyform an EL layer on the rows of pixels to luminesce a red color. Next,after moving the substrate in the lateral direction, the applicationliquid for forming the green color EL layer from the material chamber isapplied to thereby form rows of pixels to luminesce the green color. Thesubstrate is then further moved in the lateral direction so that theapplication liquid for forming the blue color EL layer from the materialchamber is applied to thereby form rows of pixels to luminesce the bluecolor.

A three-colored stripe shaped EL layer is thus formed by sequentiallyapplying the application liquid to the rows of pixels to luminesce eachof the colors red, green, and blue while moving the substrate. It is tobe noted that although only one pixel is shown in Embodiment 2, the ELlayers to luminesce the same color may be formed one row at a time orall at the same time. Further, when necessary, a mask may be providedbetween the material chamber and the substrate to thereby control theapplication position of the application liquid by applying electricfield to the mask.

As an EL material, a cyano-polyphenylene vinylene may be used for the ELlayer to luminesce a red color; a polyphenylene vinylene for the ELlayer to luminesce a green color; and a polyphenylene vinylene or apolyalkylphenylene for the EL layer to luminesce a blue color inEmbodiment 2. An appropriate film thickness thereof is 30 to 150 nm(preferably between 40 and 100 nm).

A known material may be used to form the EL layer 350. Taking thedriving voltage into consideration, it is preferable that an organicmaterial is used. It is to be noted that, in Embodiment 2, the EL layer350 is formed from the above EL material, that is, it takes a singlelayer structure of a light emitting layer only. However, an electroninjecting layer, an electron transporting layer, a hole transportinglayer, a hole injecting layer, an electron preventing layer, or a holeelement layer may be provided if necessary. Although the MgAg electrodeis used as the cathode 351 of the EL element in Embodiment 2, otherwell-known materials may be used.

The electric field application method controlled by an electric fieldhas been shown here in Embodiment 2. However, other methods such as theink jet method or a method in which the material for the EL layer iscontrolled and applied as charged particles may also be employed.

Note that although the light emitting layer is applied and formed eachcolor, in the case of forming the electron injecting layer, the electrontransporting layer, the hole transporting layer, the hole injectinglayer, the electron preventing layer, or the hole element layer, thelayers made of the different material may all be formed at once by usingmethods such as the spin coating method and the application method.

A cathode (MgAg electrode) 351 is formed by vacuum evaporation after theformation of the EL layer 350. It is to be noted that the film thicknessof the EL layer 350 may appropriately be between 80 and 200 nm(typically between 100 and 120 nm) and the thickness of the cathode 351between 180 and 300 nm (typically between 200 and 250 nm).

A protective electrode 352 is further provided on the cathode 351. Aconductive film containing aluminum as its main constituent may be usedas the protective electrode 352. The protective electrode 352 may beformed by vacuum evaporation using a mask. Note that the state of thesubstrate with the protective electrode formed on the top is referred asan active matrix substrate throughout the present specification.

A barrier layer 353 is further formed thereon so that the active matrixsubstrate that is completed up to the formation of the protectiveelectrode 352 is not exposed to the open air. In Embodiment 2, tantalumoxide is used as the material for forming the barrier layer 353.However, an inorganic material such as a silicon nitride, an aluminumnitride, or a carbon, specifically a DLC, may be used. The barrier layer353 is formed by employing sputtering In Embodiment 2, although a filmdeposition method performed at room temperature such as plasma CVD canalso be employed.

After forming the barrier layer 353, a cover layer 354 made of anorganic resin is formed on the barrier layer 353. Note that, afterdissolving the organic resin in a solvent and moderately regulating theviscosity of the organic resin itself to thereby manufacture an organicresin liquid, the organic resin liquid is then provided in the materialchamber and applied by the electric field application method, therebyforming the cover layer 354. It is preferable that the viscosity of theorganic resin liquid at this point is between 1×10⁻³ and 3×10⁻² Pa.s.

Further, at this point, the addition of an absorbent or an anti-oxidantsuch as barium oxide inside the organic resin liquid for forming thecover layer is effective in preventing moisture and oxygen, which arethe degrading factors of the EL element, from penetrating into the ELelement.

In the case of Embodiment 2, as shown in FIG. 6C, the active layer ofthe N channel TFT 205 includes a source region 355, a drain region 356,an LDD region 357 and a channel formation region 358, and the LDD region357 overlaps with the gate electrode 312 through the gate insulatingfilm 310 sandwiched therebetween.

The reason for forming the LDD region only at the side of the drainregion resides in the consideration of not dropping the operating speed.Further, it is not necessary to pay very much attention to the OFFcurrent value in the N channel TFT 205, but rather, it is better toplace importance on the operating speed. Accordingly, it is desirablethat the LDD region 357 is made to completely overlap with the gateelectrode to reduce the resistitive component to a minimum. That is, itis preferable to remove the so-called offset.

In the active matrix substrate of Embodiment 2, a TFT of an optimumstructure is not only provided in the pixel portion but also in thedriver circuit portion. Therefore, very high reliability is attained andoperating characteristics are improved.

First, a TFT with a structure that can reduce hot carrier injection soas not to drop the operating speed thereof as much as possible is usedas the N channel TFT 205 of a CMOS circuit forming the driver circuitportion. Incidentally, the driver circuit here includes a shiftregister, a buffer, a level shifter, a sampling circuit (sample and holdcircuit) and the like. In the case of performing digital driving, asignal conversion circuit such as a D/A converter is also includedtherein.

Next, the cross-sectional structure of an N channel switching TFT as theTFT of the pixel portion will be explained with reference to FIGS. 7Aand 7B. Note that the reference numerals used here correspond to thoseof FIG. 2.

First, in the structure thereof shown in FIG. 7A, the LDD regions 15 ato 15 b are provided so as not to overlap with the gate electrodes 19 aand 19 b through the gate insulating film 18 sandwiched therebetween.Such structure is very effective in lowering the OFF current value.

On the other hand, in the structure thereof shown in FIG. 7B, the LDDregions 15 a to 15 d are not provided. In the case of adopting thestructure of FIG. 7B, productivity can be improved because the number ofprocesses can be reduced when compared with case of forming thestructure of FIG. 7A.

In the present invention, a TFT may take either of the structures shownin FIGS. 7A and 7B as the switching TFT.

Next, the cross-sectional structure views of an N channel currentcontrolling TFT as the TFT of the pixel portion are illustrated in FIGS.8A and 8B. Note that the reference numerals used here correspond tothose of FIG. 2.

In the current controlling TFT shown in FIG. 8A, the LDD region 33 isprovided between the drain region 32 and the channel forming region 34.The structure of the current controlling TFT shown here has a regionwhere the LDD region 33 overlaps with the gate electrode 35 through thegate insulating film 18 sandwiched therebetween and a region where theLDD region 33 does not overlap with the gate electrode 35. However, asshown in FIG. 8B, the LDD region 33 need not be provided in thestructure thereof.

The current controlling TFT supplies a current for making the EL elementto emit light, and at the same time controls the supply amount to enablegradation display. Thus, it is necessary to take a countermeasureagainst deterioration due to the hot carrier injection so thatdeterioration does not occur even when a current is supplied.

Against deterioration caused by the hot carrier injection, it is knownthat a structure in which the LDD region overlaps with the gateelectrode is very effective. Therefore, although the structure in whichthe LDD region is provided overlapping with the gate electrode 35through the gate insulating film 18 sandwiched therebetween as shown inFIG. 8A is appropriate, as a countermeasure against the OFF currentvalue, the LDD region provided so as not to overlap with the gateelectrode is shown in the structure here. However, an LDD region notoverlapping the gate electrode does not have to be necessarily provided.In addition, the LDD regions do not have to be provided in the structureas shown in FIG. 8B depending on the situation.

In the structures of the TFT shown in FIGS. 8A and 8B, when a voltageV_(DS) that is applied to the TFT is 10 V or more, then the structureshown in FIG. 8A is preferable. On the other hand, when the voltageV_(DS) that is applied to the TFT is less than 10 V, then the structureshown in FIG. 8B is preferable.

Note that, after forming the cover layer 354 as shown in FIG. 6C andenhancing the airtightness, a connecter (flexible printed circuit: FPC)for connecting the element formed on the insulating body or a terminalled out from the circuit to an external signal terminal is attached,whereby the self-light emitting device is completed as a product. In thepresent specification, the product completed to such a state to beshipped is called the self-light emitting device (or an EL module).

The EL module of Embodiment 2 that has been formed up to the cover layeris explained here with reference to FIGS. 9A and 9B.

The active matrix type self-light emitting device of Embodiment 2includes a pixel portion 902, a gate side driver circuit 903, and asource side driver circuit 904 formed on a glass substrate 901. Aswitching TFT 905 of the pixel portion is an N channel TFT and isdisposed at an intersection of a gate wiring line 906 that is connectedto the gate side driver circuit 903 and a source wiring line 907 that isconnected to the source side driver circuit 904. Further, a drain of theswitching TFT 905 is connected to a gate of a current controlling TFT908.

Further, a source side of the current controlling TFT 908 is connectedto a power source supply line 909. In the structure such as Embodiment2, a ground electric potential (earth electric potential) is imparted tothe power source supply line 909. An EL element 910 is connected to thedrain of the current controlling TFT 908. Further, a predeterminedvoltage (3 to 12 V, preferably 3 to 5 V) is applied to the anode of theEL element 910.

Connecting wirings 912 and 913 for transmitting signals to the drivercircuit portions and a connecting wiring line 914 connected to the powersource supply line 909 are provided in an FPC 911 serving as an externalinput/output terminal.

Here, shown in FIG. 9B is a sectional view corresponding to thecross-section taken along the line A-A′ of FIG. 9A. Note that, in FIGS.9A and 9B, the same reference numerals are used to denote the samecomponents, and in a portion thereof, the same reference numerals areused to denote the same components of FIG. 6.

As shown in FIG. 9B, the pixel portion 902 and the gate side drivercircuit 903 are formed on the glass substrate 901. The pixel portion 902is composed of a plurality of pixels each including the currentcontrolling TFT 202 and the pixel electrode 348 that is electricallyconnected to the current controlling TFT 202. The gate side drivercircuit 903 is formed using a CMOS circuit in which the N channel TFT205 and the P channel TFT 206 are combined complementarity.

The pixel electrode 348 functions as an anode of the EL element. Thebank 349 is formed in the gap of the pixel electrode 348 to thereby formthe EL layer 350 on the inner side of the bank 349. The cathode 351 andthe protective electrode 352 are further formed thereon. It is to benoted that the structure of the EL element is not necessarily limited tothe structure shown in Embodiment 2, but the structure of the EL elementmay be inverted and the pixel electrode may function as the cathode.

In the case of Embodiment 2, the protective electrode 352 also functionsas a common wiring shared by all pixel rows, and is electricallyconnected to the FPC 911 via the connecting wiring 912. All of theelements contained in the pixel portion 902 and in the gate side drivercircuit 903 are covered with the barrier layer that is made of aninorganic material such as silicon nitride, tantalum oxide, or carbon(specifically a DLC film). Although it is possible to omit the barrierlayer 353, the provision of the barrier layer 353 is preferred in termsof shielding the respective elements from the outside.

Next, a cover layer 916 is provided on the barrier layer so as to coverthe EL element. As the cover layer 916, PVC (polyvinyl chloride), epoxyresin, silicone resin, acrylic resin, PVB (polyvinyl butylal), or EVA(ethylenevinyl acetate) may be used. An absorbent (not shown) placedinside the cover layer 916 keeps moisture absorbing effect, which ispreferable.

A protecting substrate that is made of glass, plastic, and ceramic canbe provided on the cover layer 916. In addition, the structure may beone in which the protecting substrate (not shown in the figure) isbonded to the active matrix substrate by using the cover layer 916.

By providing the barrier layer 353 and the cover layer 916 on the ELelement 910 using the method as described above, the EL element 910 maybe completely cut off from the external environment and the invasionfrom the outside by substances that accelerate the oxidation degradationof the EL layer, such as moisture and oxygen, can thus be prevented.Accordingly, a self-light emitting device with high reliability can bemanufactured.

An example of a circuit configuration of the self-light emitting deviceshown in FIG. 9 is illustrated in FIG. 10. The self-light emittingdevice of Embodiment 2 includes a source side driver circuit 1001, agate side driver circuit (A) 1007, a gate side driver circuit (B) 1011,and a pixel portion 1006. Note that, in the present specification, theterm “driver circuit portion” is a generic term including the sourceside processing circuit and the gate side driver circuit.

The source side driver circuit 1001 is provided with a shift register1002, a level shifter 1003, a buffer 1004, and a sampling circuit(sample and hold circuit) 1005. Further, the gate side driver circuit(A) 1007 is provided with a shift register 1008, a level shifter 1009,and a buffer 1010. The gate side driver circuit (B) 1011 also takes thesame structure.

Here, the shift registers 1002 and 1008 have driving voltages of 5 to 16V (typically 10 V), respectively, and the structure indicated by thereference numeral 205 in FIG. 6C is suitable for the N channel TFT thatis used in a CMOS circuit for forming the circuits.

Besides, the CMOS circuit including the N channel TFT 205 in FIG. 6C issuitable for each of the level shifters 1003 and 1009 and the buffers1004 and 1010, similarly to the shift register. Incidentally, the gatewiring with multi-gate structure such as a double gate structure or atriple gate structure is effective in improving the reliability of eachcircuit. The pixel with the structure illustrated in FIG. 2 is arrangedin the pixel portion 1006.

The foregoing structure can be easily realized by manufacturing TFTs inaccordance with the manufacturing steps shown in FIGS. 4A to 6C. InEmbodiment 2, although only the structure of the pixel portion and thedriver circuit portion is shown, it is possible to form not only thedriver circuit, but also a logical circuit such as a signal dividingcircuit, a D/A converter circuit, an operational amplifier circuit, a{overscore (a)}-correction circuit on the same insulating body if themanufacturing steps of the circuits are carried out in accordance withthose of Embodiment 2. In addition, it is believed that a memoryportion, a microprocessor, or the like can be formed.

The constitution of Embodiment 2 can be freely combined with theconstitution of Embodiment 1.

Embodiment 3

A method of manufacturing a lamination structure that is different fromthe one shown in FIG. 1B will be explained in Embodiment 3. In FIG. 11,a current controlling TFT 1101 is formed on a substrate 1100, and apixel electrode 1102 electrically connected to the current controllingTFT 1101 is formed as illustrated in the drawing. In Embodiment 3, an ELlayer 1103 is formed on the pixel electrode 1102 using the ink jetmethod. Note that it is appropriate to use the same material used inEmbodiment 1 for the application liquid for the EL layer.

Provided on the EL layer 1103 is a cathode 1104 formed using theevaporation method. Note that it is appropriate to use a material thathas a small work function, such as MgAg and Al—Li, for forming thecathode 1104. After forming the cathode 1104, the ink jet method isagain used to form a cover layer 1105 made of an organic resin filmevenly on the pixel portion. Preferably, the film thickness of the coverlayer 1105 formed is between 10 nm and 300 nm.

As a material for forming the cover layer 1105 made of an organic resin,it is appropriate to use a material that has a high degree of hardness,is unlikely to allows substances such as moisture and oxygen topermeate, and has planarity. To be more specific, organic resins such asepoxy resin, acrylic resin, polyimide, polyamide, and silicon resin arepreferable. Because the cover layer 1105 is formed using the ink jetmethod, it can be selectively formed on the pixel portion.

Shown in FIG. 12 is the method of forming a cover layer 1202 on a pixelportion 1201 on an active matrix substrate 1200 by using the ink jetmethod. Note that, the application liquid for forming the EL layer andthe organic resin liquid for forming the cover layer are discharged froma head 1203 in the structure shown here. Note that in the Piezo methodknown for the ink jet method, there are types, one being the MLP (MultiLayer Piezo) type and the other being the MLChip (Multi Layer CeramicHyper Integrated Piezo Segments) type. The head 1203 shown here is onecalled On Demand Piezo Driver MLChip method that is manufactured bySeiko-Epson Corp.

The MLChip is an actuator composed of an oscillation plate 1204 made ofceramic, a communicating plate 1205, and a material chamber plate 1206that forms the material chamber 1207, and piezo elements 1208 are formedon the vibrator plate 1204 in correspondence with each of the materialchambers.

Then, in the MLChip, three stainless plates (SUS plate) are laminated toform a supply hole 1209, a reserver 1210, and a nozzle 1211 whichthereby form a head 1203. It is to be noted FIG. 12 shows a state wheretwo nozzles 1211 are provided. However, the number of nozzles is notlimited thereto, but one nozzle may be provided or three or more may beprovided depending on the region to be applied and the applicationliquid.

The operating principle of the application device fabricated from thisMLChip is that when a voltage is applied to a top electrode 1212 and abottom electrode 1213, the piezo elements 1208 vibrate to thereby causea piezoelectric effect of the piezo elements 1208 and the vibrator plate1204, that is, a bending vibration. In other words, pressure is appliedto the material chamber 1207 by this bending vibration, whereby theorganic resin liquid provided in the material chamber 1207 is pushed outand then applied.

As shown in FIG. 11, after the formation of the cover layer 1105, abarrier layer 1106 is formed by sputtering to cover the cover layer1105. In Embodiment 3, the barrier layer 1106 is formed of a carbonfilm, specifically a DLC (Diamond Like Carbon) film. However, thematerial for forming the barrier layer 1106 is not necessarily limitedthereto, but materials such as tantalum oxide, aluminum nitride, orsilicon nitride may also be used. It is note that the barrier layer 1106is formed selectively using a shadow mask.

Thus, by forming the cover layer 1105 and the barrier layer 1106 on theactive matrix substrate, the invasion of degrading factors to the ELelement, such as moisture and oxygen, from the outside can be prevented.

Embodiment 4

A case of employing the present invention in a passive type (simplematrix type) self-light emitting device is explained in Embodiment 4with reference to FIG. 13. In FIG. 13, reference numeral 1301 denotes asubstrate made of plastic and 1302 denotes an anode made of atransparent conductive film. A compound of indium oxide and zinc oxideis formed by sputtering as the anode 1302 in Embodiment 4. Note that,although not shown in FIG. 13, a plural number of lines of anodes 1302are arranged in stripe shapes in a parallel direction with the definedspace.

Further, cathodes 1306 arranged in stripe shapes are formed in aperpendicular direction on the defined space. Banks 1303 are formed soas to fill up the spaces between the cathodes 1306.

Subsequently, EL layers 1304 a to 1304 c made of an EL material areformed by using the electric field application method described inEmbodiment 1. Note that, reference numeral 1304 a denotes an EL layerluminescing a red color, 1304 b denotes an EL layer luminescing a greencolor, and 1304 c denotes an EL layer luminescing a blue color. An ELmaterial used in Embodiment 1 may be used similarly in Embodiment 4.Since these EL layers are formed along the grooves which are formed bythe banks 1303, these layers are arranged in stripe shapes in aperpendicular direction on the defined space.

By implementing the present embodiment, pixels of three colors, red,green, and blue, are formed on the substrate in stripe shapes. It shouldbe noted that the pixels need not to have three colors, but may have oneor two colors. In addition, the colors are not limited to red, green,and blue, but other colors such as yellow, orange and gray may be used.

First, the application liquid for forming a red color EL layer isprepared in the material chamber. The application liquid is thenextracted by an electric field generated by an electrode provided on theexterior of the material chamber. The extracted application liquid forthe EL layer is controlled by electric field, whereby it reaches thedesired pixel portion. The EL layer is thus formed.

The application liquid for the red color EL layer is first applied.Because the application liquid is controlled by the electric field, theapplication liquid for the EL layer can be selectively applied onto thedesired position of the pixel portion. Note that it is appropriate toapply the application liquid while moving the nozzle in the direction offorming one row of pixels.

Subsequently, after moving the nozzle to the adjacent row of pixels sothat an application can be performed, the application liquid for thegreen color EL layer is applied. After further moving the nozzle to thenext adjacent row of pixels, the application liquid for the blue colorEL layer is applied to thereby form stripe shape EL layers of red,green, and blue in the pixel portion.

By repeating the above operation, stripe shape pixels can be formed inthe pixel portion as shown in FIG. 13. Note that light emitting layersluminescing the same color may be formed one at a time or all at thesame time.

Although the EL layer here denotes an EL layer of a single structurecomposed of only the light emitting layer, other layers formed from anorganic EL material that contributes to the emission of light, such asan electric charge injection layer and an electric charge transportinglayer, may also be used. There are cases where a single layer of thelight emitting layer is adopted. However, for example, in the case ofadopting a lamination layer composed of the hole injection layer and thelight emitting layer, the lamination film is referred as an EL layer.

At this point, it is preferable that a mutual distance (D) of adjacentpixels of the same color in a line is set to 5 times or more (preferably10 times or more) higher than the film thickness (t) of the EL layer.This is because a problem of cross-talk will occur between the pixels ifD<5t. It should be noted if the distance (D) is too far apart from eachother, then highly fine images can not be attained. Therefore, settingthe distance (D) to 5t<D<50t (preferably 10t<D<35t) is preferable.

Further, it is possible to form the bank in a stripe shape in thehorizontal direction to thereby form the EL layer luminescing a redcolor, the EL layer luminescing a green color, and the EL layerluminescing a blue color in the horizontal direction. At this point, thebank is formed above the gate wiring through the insulating film andalong the gate wiring.

In this case, similarly, it is appropriate to set the mutual distance(D) of adjacent pixels of the same color in a line to 5 times or more(preferably 10 times or more) higher than the film thickness (t) of theEL layer, and more preferably to 5t<D<50t (preferably 10t<D<35t).

Thus, the application liquid for the EL layer is controlled by anelectric field to thereby form the EL layer, resulting in making itpossible to control the application position.

Thereafter, although not shown in FIG. 13, the cathodes and protectiveelectrodes are arranged in stripe shapes so as to be orthogonal to theanodes 1302 and so that the perpendicular direction of a plural numberof lines of cathodes and protective electrodes on the defined spacebecome the longitudinal direction. Note that the cathode 1305 is madefrom MgAg and the protective electrode 1306 is made from an aluminumalloy film, and the both are respectively formed by evaporation inEmbodiment 4. Furthermore, a wiring, not shown in the drawing, is drawnto a portion where an FPC will be attached later so that a predeterminedvoltage can be applied to the protective electrode 1306.

An EL element is thus formed on the substrate 1301. Note that since alower side electrode serves as a transmissive anode in Embodiment 4,light generated by the EL layers 1304 a to 1304 c is irradiated to alower surface (substrate 1301). However, the lower side electrode canserve as a light shielding cathode by reversing the structure of the ELelement. In that case, light generated by the EL layers 1304 a to 1304 cis irradiated to an upper surface (the side opposite the substrate1301).

After the formation of the protective electrode 1306, a barrier layer1307 made of an inorganic material is formed. It is appropriate here touse inorganic materials such as silicon nitride, tantalum oxide,aluminum nitride, or carbon (specifically a DLC film). The barrier layercan be formed by plasma CVD, sputtering, or evaporation. A siliconnitride film is formed by sputtering as the barrier layer 1307 inEmbodiment 4. At this point, a preferable film thickness of the barrierlayer 1307 is between 10 nm and 100 nm.

A cover layer 1308 made of an organic resin film is subsequently formedby the same method used for forming the EL layer. Note that it isappropriate to use materials such as polyamide and polyimide as theorganic resin used here. Further, barium oxide may be doped into theorganic resin film as an absorbent (not shown in the figure). Finally,an FPC 1310 is attached via an anisotropic conductive film 1309, therebycompleting the passive type self-light emitting device.

The passive type self-light emitting device shown in FIG. 13 has astructure in which the barrier layer 1307 is formed on the EL elementover the substrate, and the cover layer 1308 is formed on the barrier1307. However, as shown in FIG. 14, the structure in which a barrierlayer 1408 is formed after forming a cover layer 1407 may be adopted.

It is to be noted that the constitution of Embodiment 4 may beimplemented freely combining with any one of the constitutions ofEmbodiments 1 to 3.

Embodiment 5

In the present invention, it is effective to use a DLC (Diamond LikeCarbon) film made of carbon as the barrier layer. However, if the filmthickness thereof is too thick, transmissivity will drop, and thereforeit is preferable to form the film thickness thereof to 50 nm or less(preferably between 10 and 20 nm).

A characteristic of the DLC film is that it has a Raman spectrumdistribution with a asymmetric peak of about 1550 cm⁻¹ and a shoulder ofabout 1300 cm⁻¹. In addition, the DLC film shows a hardness of 15 to 25Gpa when measured using a microhardness meter and has a characteristicthat it is superior to chemical resistance. Therefore, it is effectiveto form such DLC film on the EL element or on the cover layer on the ELelement. In any case, appropriately, the DLC film may be formed by usingmethods such as sputtering, ECR plasma CVD, high frequency plasma CVD,or ion beam evaporation.

It is to be noted that the constitution of Embodiment 5 may beimplemented freely combining with any one of the constitutions ofEmbodiments 1 to 4.

Embodiment 6

When the present invention is implemented to manufacture an activematrix self-light emitting display device, it is effective to use asilicon substrate (silicon wafer) as a substrate. In the case of usingthe silicon substrate as the substrate, a manufacturing technique ofMOSFET utilized in the conventional IC, LSI or the like can be employedto manufacture a switching element and a current control element to beformed in the pixel portion, or a driver element to be formed in thedriver circuit portion.

The MOSFET can form circuits having extremely small variations asachievements in the IC and the LSI. Particularly, it is effective forthe active matrix EL display device with an analog driver of performinggradation display by an electric current value.

It is to be noted that the silicon substrate is not transmissive, andtherefore the structure needs to be constructed so that light from theEL layer is irradiated to a side opposite the substrate. The structureof the EL display device of Embodiment 5 is similar to that of FIG. 9.However, the difference is that the MOSFET is used for forming a pixelportion 902 and a driver circuit portion 903 instead of a TFT.

Note that it is possible to implement the structure of Embodiment 5freely combining it with the structure of any of Embodiments 1 to 5.

Embodiment 7

The self-emission device fabricated in accordance with the presentinvention is of the self-emission type, and thus exhibits more excellentrecognizability of the displayed image in a light place as compared tothe liquid crystal display device. Furthermore, the self-emission devicehas a wider viewing angle. Accordingly, the self-emission device can beapplied to a display portion in various electronic devices. For example,in order to view a TV program or the like on a large-sized screen, theEL display device in accordance with the present invention can be usedas a display portion of an EL display (i.e., a display in which aself-emission device is installed into a frame) having a diagonal sizeof 30 inches or larger (typically 40 inches or larger.)

The EL display includes all kinds of displays to be used for displayinginformation, such as a display for a personal computer, a display forreceiving a TV broadcasting program, a display for advertisementdisplay. Moreover, the self-emission device in accordance with thepresent invention can be used as a display portion of other variouselectric devices.

Such electronic devices include a video camera, a digital camera, agoggles-type display (head mount display), a navigation system, a soundreproduction device (a car audio equipment and an audio set), note-sizepersonal computer, a game machine, a portable information terminal (amobile computer, a portable telephone, a portable game machine, anelectronic book, or the like), an image reproduction apparatus includinga recording medium (more specifically, an apparatus which can reproducea recording medium such as a digital video disc (DVD) and so forth, andincludes a display for displaying the reproduced image), or the like. Inparticular, in the case of the portable information terminal, use of theself-emission device is preferable, since the portable informationterminal that is likely to be viewed from a tilted direction is oftenrequired to have a wide viewing angle. FIGS. 15A to 16B respectivelyshow various specific examples of such electronic devices.

FIG. 15A illustrates an EL display which includes a frame 2001, asupport table 2002, a display portion 2003, or the like. The presentinvention is applicable to the display portion 2003. The EL display isof the self-emission type and therefore requires no back light. Thus,the display portion thereof can have a thickness thinner than that ofthe liquid crystal display device.

FIG. 15B illustrates a video camera which includes a main body 210l, adisplay portion 2102, an audio input portion 2103, operation switches2104, a battery 2105, an image receiving portion 2106, or the like. Theself-emission device in accordance with the present invention can beused as the display portion 2102.

FIG. 15C illustrates a portion (the right-half piece) of an EL displayof head mount type, which includes a main body 2201, signal cables 2202,a head mount band 2203, a display portion 2204, an optical system 2205,a self-emission device 2206, or the like. The present invention isapplicable to the self-emission device 2206.

FIG. 15D illustrates an image reproduction apparatus including arecording medium (more specifically, a DVD reproduction apparatus),which includes a main body 2301, a recording medium (a DVD or the like)2302, operation switches 2303, a display portion (a) 2304, anotherdisplay portion (b) 2305, or the like. The display portion (a) is usedmainly for displaying image information, while the display portion (b)is used mainly for displaying character information. The self-emissiondevice in accordance with the present invention can be used as thesedisplay portions (a) and (b). The image reproduction apparatus includinga recording medium further includes a game machine or the like.

FIG. 15E illustrates a portable (mobile) computer which includes a mainbody 2401, a camera portion 2402, an image receiving portion 2403,operation switches 2404, a display portion 2405, or the like. Theself-emission device in accordance with the present invention can beused as the display portion 2405.

FIG. 15F illustrates a personal computer which includes a main body2501, a frame 2502, a display portion 2503, a key board 2504, or thelike. The self-emission device in accordance with the present inventioncan be used as the display portion 2503.

When the brighter luminance of light emitted from the organic ELmaterial becomes available in the future, the self-emission device inaccordance with the present invention will be applicable to a front-typeor rear-type projector in which light including output image informationis enlarged by means of lenses or the like to be projected.

The forementioned electronic devices are more likely to be used fordisplay information distributed through a telecommunication path such asInternet, a CATS (cable television system), and in particular likely todisplay moving picture information. The self-emission device is suitablefor displaying moving pictures since the organic EL material can exhibithigh response speed. However, if the contour between the pixels becomesunclear, the moving pictures as a whole cannot be clearly displayed.Since the self-emission device in accordance with the present inventioncan make the contour between the pixels clear, it is significantlyadvantageous to apply the self-emission device of the present inventionto a display portion of the electronic devices.

A portion of the self-emission device that is emitting light consumespower, so it is desirable to display information in such a manner thatthe light emitting portion therein becomes as small as possible.Accordingly, when the self-emission device is applied to a displayportion which mainly displays character information, e.g., a displayportion of a portable information terminal, and more particular, aportable telephone or a sound reproduction device, it is desirable todrive the self-emission device so that the character information isformed by a light-emitting portion while a non-emission portioncorresponds to the background.

With now reference to FIG. 16A, a portable telephone is illustrated,which includes a main body 2601, an audio output portion 2602, an audioinput portion 2603, a display portion 2604, operation switches 2605, andan antenna 2606. The self-emission device in accordance with the presentinvention can be used as the display portion 2604. The display portion2604 can reduce power consumption of the portable telephone bydisplaying white-colored characters on a black-colored background.

FIG. 16B illustrates a sound reproduction device, a car mounted audioequipment in concrete term, which includes a main body 2701, a displayportion 2702, and operation switches 2703 and 2704. The self-emissiondevice in accordance with the present invention can be used as thedisplay portion 2702. Although the car audio equipment of the mount typeis shown in the present embodiment, the present invention is alsoapplicable to an audio of the portable type and the set type. Thedisplay portion 2704 can reduce power consumption by displayingwhite-colored characters on a black-colored background, which isparticularly advantageous for the audio of the portable type.

As set forth above, the present invention can be applied variously to awide range of electronic devices in all fields. The electronic device inthe present embodiment can be obtained by utilizing a self-emissiondevice having the configuration in which the structures in Embodiments 1through 6 are freely combined.

Embodiment 8

In this embodiment, an external light emitting quantum efficiency can beremarkably improved by using an EL material by which phosphorescencefrom a triplet exciton can be employed for emitting a light. As aresult, the power consumption of the EL element can be reduced, thelifetime of the EL element can be elongated and the weight of the ELelement can be lightened.

The following is a report where the external light emitting quantumefficiency is improved by using the triplet exciton (T. Tsutsui, C.Adachi, S. Saito, Photochemical processes in organized molecularsystems, ed. K. Honda, (Elsevier Sci. Pub., Tokyo, 1991) p. 437).

The molecular formula of an EL material (coumarin pigment) reported bythe above article is represented as follows.

(M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E.Thompson, S. R. Forrest, Nature 395(1998) p. 151)

The molecular formula of an EL material (Pt complex) reported by theabove article is represented as follows.

(M. A. Baldo, S. Lamansky, P. E. Burrows, M. E. Thompson, S. R. Forrest,Appl. Phys. Lett., 75 (1999) p.4.)

(T. Tsutsui, M. -J. Yang, M. Yahiro, K. Nakamura, T. Watanabe, T. Tsuji.Y. Fukuda, T. Wakimoto, S. Mayaguchi, Jpn, Appl. Phys., 38 (12B) (1999)L1502)

The molecular formula of an EL material (Ir complex) reported by theabove article is represented as follows.

As described above, if phosphorescence from a triplet exciton can beused, it can be realized that the external light emitting quantumefficiency is three to fourth times as high as that in the case of usingfluorescence from a singlet exciton in principle.

The structure according to Embodiment 8 can be freely implemented incombination wiyh any structures of the Embodiments 1 to 7.

By implementing the present invention, the EL layer and the cover layercan be formed by using the same application method and t is possible toeffectively form the EL layer, the cathode, the barrier layer, and thecover layer in the same multi-chamber in succession without releasingthem to the atmosphere. In addition, by forming the barrier layer andthe cover layer, the permeation of moisture and oxygen into the EL layeris prevented. Thus, it is an effective against degradation of the ELlayer. Further, forming the barrier layer and the cover layer completethe sealing structure, and hence compared with a normal sealingstructure, it becomes possible to make the sealing structure of thepresent invention more smaller and lighter in weight.

1-22. (Cancelled)
 23. A method of manufacturing a light emitting devicecomprising: forming an EL element comprising a first electrode, a lightemitting layer over the first electrode, and a second electrode over thelight emitting layer; forming a film comprising an inorganic materialcovering the EL element; and forming a film comprising an organicmaterial covering the film comprising said inorganic material, whereinthe light emitting layer and said film comprising an organic materialare formed by an ink jet method, and wherein the light emitting layercomprises a low molecular material.
 24. A method of manufacturing alight emitting device according to claim 23, wherein the film comprisingan inorganic material comprises one of silicon nitride, tantalum oxide,aluminum nitride, or carbon.
 25. A method of manufacturing a lightemitting device according to claim 23, wherein the film comprising anorganic material comprises one of polyamide, polyimide, acrylic resin,or benzocyclobuten.
 26. A method of manufacturing a light emittingdevice according to claim 23, wherein the light emitting device isincorporated into an electronic appliance selected from the groupconsisting of a video camera, a head mount type display, an imagereproduction apparatus, a portable computer, a personal computer, aportable telephone, and a sound reproduction device.
 27. A method ofmanufacturing a light emitting device comprising: forming an EL elementcomprising a first electrode, a light emitting layer over the firstelectrode, and a second electrode over the light emitting layer; forminga film comprising an inorganic material covering the EL element; andforming a film comprising an organic material covering the filmcomprising said inorganic material, wherein the light emitting layer andsaid film comprising an organic material are formed by an electric fieldapplication method, and wherein the light emitting layer comprises a lowmolecular material.
 28. A method of manufacturing a light emittingdevice according to claim 27, wherein the film comprising an inorganicmaterial comprises one of silicon nitride, tantalum oxide, aluminumnitride, or carbon.
 29. A method of manufacturing a light emittingdevice according to claim 27, wherein the film comprising an organicmaterial comprises one of polyamide, polyimide, acrylic resin, orbenzocyclobuten.
 30. A method of manufacturing a light emitting deviceaccording to claim 27, wherein the light emitting device is incorporatedinto an electronic appliance selected from the group consisting of avideo camera, a head mount type display, an image reproductionapparatus, a portable computer, a personal computer, a portabletelephone, and a sound reproduction device.
 31. A method ofmanufacturing a light emitting device comprising: forming an EL elementcomprising a first electrode, a light emitting layer over the firstelectrode, and a second electrode over the light emitting layer; forminga film comprising an inorganic material covering the EL element; andforming a film comprising an organic material covering the filmcomprising said inorganic material, wherein the light emitting layer andsaid film comprising an organic material are formed by a same method,wherein the light emitting layer comprises a low molecular material, andwherein the light emitting layer, the second electrode, the filmcomprising an inorganic material, and the film comprising an organicmaterial are formed continuously using the same film depositionapparatus.
 32. A method of manufacturing a light emitting deviceaccording to claim 31, wherein the film comprising an inorganic materialcomprises one of silicon nitride, tantalum oxide, aluminum nitride, orcarbon.
 33. A method of manufacturing a light emitting device accordingto claim 31, wherein the film comprising an organic material comprisesone of polyamide, polyimide, acrylic resin, or benxocyclobuten.
 34. Amethod of manufacturing a light emitting device according to claim 31,wherein the light emitting device is incorporated into an electronicappliance selected from the group consisting of a video camera, a headmount type display, an image reproduction apparatus, a portablecomputer, a personal computer, a portable telephone, and a soundreproduction device.
 35. A method of manufacturing a light emittingdevice comprising: forming an EL element comprising a first electrode, alight emitting layer over the first electrode, and a second electrodeover the light emitting layer; forming a film comprising an organicmaterial covering the EL element; and forming a film comprising aninorganic material covering the film comprising said organic material,wherein the light emitting layer and said film comprising an organicmaterial are formed by an ink jet method, and wherein the light emittinglayer comprises a low molecular material.
 36. A method of manufacturinga light emitting device according to claim 35, wherein the filmcomprising an inorganic material comprises one of silicon nitride,tantalum oxide, aluminum nitride, or carbon.
 37. A method ofmanufacturing a light emitting device according to claim 35, wherein thefilm comprising an organic material comprises one of polyamide,polyimide, acrylic resin, or benzocyclobuten.
 38. A method ofmanufacturing a light emitting device according to claim 35, wherein thelight emitting device is incorporated into an electronic applianceselected from the group consisting of a video camera, a head mount typedisplay, an image reproduction apparatus, a portable computer, apersonal computer, a portable telephone, and a sound reproductiondevice.
 39. A method of manufacturing a light emitting devicecomprising: forming an EL element comprising a first electrode, a lightemitting layer over the first electrode, and a second electrode over thelight emitting layer; forming a film comprising an organic materialcovering the EL element; and forming a film comprising an inorganicmaterial covering the film comprising said organic material, wherein thelight emitting layer and said film comprising an organic material areformed by an electric field application method, and wherein the lightemitting layer comprises a low molecular material.
 40. A method ofmanufacturing a light emitting device according to claim 39, wherein thefilm comprising an inorganic material comprises one of silicon nitride,tantalum oxide, aluminum nitride, or carbon.
 41. A method ofmanufacturing a light emitting device according to claim 39, wherein thefilm comprising an organic material comprises one of polyamide,polyimide, acrylic resin, or benzocyclobuten.
 42. A method ofmanufacturing a light emitting device according to claim 39, wherein thelight emitting device is incorporated into an electronic applianceselected from the group consisting of a video camera, a head mount typedisplay, an image reproduction apparatus, a portable computer, apersonal computer, a portable telephone, and a sound reproductiondevice.
 43. A method of manufacturing a light emitting devicecomprising: forming an EL element comprising a first electrode, a lightemitting layer over the first electrode, and a second electrode over thelight emitting layer; forming a film comprising an organic materialcovering the EL element; and forming a film comprising an inorganicmaterial covering the film comprising said organic material, wherein thelight emitting layer and said film comprising an organic material areformed by a same method, wherein the light emitting layer comprises alow molecular material, and wherein the light emitting layer, the secondelectrode, the film comprising an inorganic material, and the filmcomprising an organic material are formed continuously using the samefilm deposition apparatus.
 44. A method of manufacturing a lightemitting device according to claim 43, wherein the film comprising aninorganic material comprises one of silicon nitride, tantalum oxide,aluminum nitride, or carbon.
 45. A method of manufacturing a lightemitting device according to claim 43, wherein the film comprising anorganic material comprises one of polyamide, polyimide, acrylic resin,or benzocyclobuten.
 46. A method of manufacturing a light emittingdevice according to claim 43, wherein the light emitting device isincorporated into an electronic appliance selected from the groupconsisting of a video camera, a head mount type display, an imagereproduction apparatus, a portable computer, a personal computer, aportable telephone, and a sound reproduction device.